Gas blast circuit breaker



Aug. 18, 1942. H THOMMEN 2,293,320

GAS BLAST CIRCUIT BREAKER Filed July 25, 1940 Patented Aug. 18, 1942 GAS BLAST CIRCUIT BREAKER Hans Thommen, Baden, Switzerland, assigner to Aktiengesellschaft Brown,

Boveri & Cie.,

Baden, Switzerland, a joint-stock company Application July 23, 1940, Serial No. 347,008 In Switzerland July 26, 1939 (Cl. ZOO- 148) 6 Claims.

The invention concerns a circuit breaker in which the arc is extinguished by means of a blast of extinguishing medium, the circuit breaker having at least one hollow contact through which the extinguishing medium flows, the contacts of the circuit breaker being bridged over by a protective resistance which is switched in by means of an auxiliary contact which is swept over by the interrupting arc. The object of the protective resistance is to retard the speed with which the recovery voltage rises after the are has been extinguished. If the gas blast circuit breaker is connected in series with a second switch point, the power being interrupted by the former and the voltage by the latter, the series-connected switch point can be a simple air break switch because it has only to interrupt the residual current which is limited by the resistance. It has been found that particularly with circuit breakers of this kind where there is a nozzle contact and a movable contact part located opposite to the nozzle, after the main arc has been extinguished it is difiicult to extinguish the auxiliary arc prevailing between one of the main contacts and the auxiliary contact for switching in the resistance, with the result that the operation of the circuit breaker is detrimentally affected. In order to overcome this disadvantage, according to the invention the auxiliary contact is arranged to lie in the axis of flow of the extinguishing medium and furthermore subdividing partitions are built into the outlet passage through which the extinguishing medium flows, the auxiliary arc between the auxiliary contact and the hollow contact brushing against these partitions.

The objects and advantages of the invention will be apparent from the following specication when taken with the accompanying drawing, in which a circuit breaker is shown diagrammatically in section, all those details which are not essential for an understanding of the invention having been omitted.

In the gure, a designates a switch chamber of an air blast circuit breaker the upper part of which is formed by means of the stationary hollow contact b and which is supplied with compressed air in a known manner through conduit 7 of insulating material. The movable countercontact c is located in the switch chamber and guided therein. The auxiliary contact e for switching in the protective resistance d is arranged to lie coaxial with and spaced axially from the hollow contact b in the direction of flow of the air blast through the outlet passage f. The Space between the auxiliary contact and the insulating wall of the outlet passage f is subdivided by the partitions g. In the constructional example shown in the drawing the outlet passage has a cylindrical shape so that the partitions g form concentric cylinders.

The arc initially drawn between hollow contact b and movable contact c upon movement of contact c to extinguishing position is elongated by the air blast to form an inverted loop that strikes the auxiliary contact e, thus momentarily forming an arc having two branches, one between the movable contact c and the auxiliary contact e and the other between the auxiliary contact e and the hollow contact b. The first named arc is rapidly deionized by the compressed air blast and extinguished, whilst the second arc is blown by the compressed air towards the ends of the partitions g which when they are made of metal cause the arc to be split up and extinguished. Instead .of making the partitions g entirely of metal it is of course possible to make only the ends nearest to the arc of metal and the remaining portion of insulating material. The parti tions g can also consist entirely of insulating material, for instance gas producing insulating material, which helps to extinguish the are. The extinguishing action can also be further assisted by throttling the air in the outlet passage. This can be achieved by arranging a throttling device, for instance a silencer or cooler h, in front of the partitions in the direction of air flow through the outlet passage.

The movable contact c can also be designed as a hollow contact and both contacts can be made to move towards each other. The protective resistance d can be arranged on the outside wall of the outlet passage for the extinguishing medium as shown in the drawing. It is also possible to wind the resistance in such a manner that there are at least two layers through which the current flows in opposite directions.

I claim:

1. In a circuit breaker of the type in which the arc is extinguished by a blast of extinguishing medium, a pair of cooperating arcing contacts supported for relative movement, at least one of said contacts being hollow, means cooperating with said hollow contact to establish a blast of arc extinguishing medium therethrough upon a separation of said cooperating contacts, an insulating member forming an outlet passage for the extinguishing medium discharged through the hollow contact, an auxiliary contact positioned within said outlet passage in axial alinement with and spaced axially from the hollow 3. In a circuit breaker, the invention as claimed in claim 1, wherein said subdividing partitions are metal cylinders.

4. In a circuit breaker, the invention as claimed in claim 1, wherein said resistance is arranged l upon the outside wall of said outlet passage.

5` In a circuit breaker, the invention as claimed in claim 1, wherein said resistance is arranged upon the outside Wall of said outlet passage and comprises at least two layers wound in opposite sense.

6. In a circuit breaker, the invention as claimed in claim 1, in combination with a throttling device for the extinguishing medium in the outlet passage and beyond said partitions in the direction of iiow of the extinguishing medium.

HANS THOMMEN. 

